The widespread use of new, cleaner-burning fuel formulations, including those containing methanol, is increasingly likely. Unfortunately, some of the alternate fuels under consideration are more chemically active than gasoline and have been found to have an adverse effect on many components of fuel handling systems. Therefore, the search continues for cost-effective sealing and fuel-handling materials that will not degrade in the presence of methanol-containing fuels.This paper examines the impact of three fuels, Fuel C and two blends of Fuel C and methanol, on standard automotive O-rings fabricated from two grades of fluorosilicone elastomers and one grade of fluorocarbon elastomer.